Method and apparatus for dressing grinding wheels



Feb. 26, 1952 E. WILDHABER METHOD AND APPARATUS FOR DRESSING GRINDING WHEELS Filed Dec. 29, 1945 6 Sheets-Sheet l LDHABER INVENTOR.

FIG 6 ERNEST w| Feb. 26, 1952 E; WILDHABER METHOD AND APPARATUS FOR DRESSING GRINDING WHEELS s Sheets-Shet 2 Filed Dec. 29, 1945 ERNEST WILDHABER INVENTOR.

I BY 2 1 Feb. 26, 1952 E. WILDHABER 2,587,261

METHOD AND APPARATUS FOR DRESSING GRINDING WHEELS Filed Dec. 29, 1945 6 Sheet .s-Sheet 5 ERNEST WILDHABER IN V EN TOR.

Feb. 26, 1952 E. WILDHABER METHOD AND APPARATUS FOR DRESS ING GRINDING WHEELS 6 Sheets-Sheet 4 Filed Dec.. 29, 1945 IOO FIG. l5 FIG.'I6

ERNEST WILDHABER INVENTOR.

Feb. 26, 1952 E. WILDHABER METHOD AND APPARATUS FOR DRESSING GRINDING WHEELS 6 Sheets-Sheet 5 Filed Dec. 29, 1945 ERNEST WILDHABER INVENTOR.

Patented Feb. 26, 1952 METHOD AND APPARATUS FOR DRESSING GRINDING WHEELS Ernest Wildhaber, Brighton, N. Y., assignor to Gleason Works, Rochester, N. Y., a corporation of New York Application December 29, 1945, Serial No. 638,029

19 Claims.

The present invention relates to methods and apparatus for dressing grinding wheels and particularly to methods and apparatus for dressing wheels, such as are used in grinding tooth surfaces of gears, face clutch members, and the like.

In the production of face clutch members, it is customary to chamfer or round off the tops of the teeth to facilitate engagement of the mating clutch members or to prevent interference of the top of a tooth of one member with the lower, flank portion of the tooth of the mating member. To produce the chamfer or round in a grinding operation, it is preferable to have a shoulder on the side of the grinding wheel which matches the straight or curved chamfer to be produced on the clutch teeth so that the sides of the teeth and the chamfered or roundedportions thereof may be ground simultaneously. Difliculty has been experienced, heretofore, however, in dressing the desired shape of shoulder on a wheel especially where the shoulder has had a substantial inclination to the side surface of the wheel, say more than 6. The result has been that frequently it has been necesary to grind the sides of the teeth of a face clutch member in one operation and the chamfer or rounds in a separate operation.

.I-Ieretofore, moreover, whether shoulders have had to be dressed on the wheels or not, separate side and end dressing tools have been employed in dressing wheels which are intended to grind gears and face clutch members. Usually two tools at least, viz., a side dresser and an end dresser, have had to be employed for dressing a wheel for grinding clutch members and ordinarily, at least three tools, viz., two side dressers and an end dresser, have had to be employed for dressing a wheel for grinding gear teeth. Aside from their complication, therefore, the dressing mechanisms used heretofore have had the disadvantage that they do not dress a single continuous profile around the sides and tip of the wheel. The path of the end dresser intersects the path or paths of the side dressers at a slight angle, and there are slight angles, therefore, where the side and end dressers, respectively, leave off. Moreover, the unequal wear of the several diamonds causes imperfect blending of the dresser paths, and continuous resetting.

of the dresser tools is necessary.

One object of the present invention-ism provide a dressing mechanism with which a grind-L tinuous operation without any break in the profile outline. I

Another object of the invention is to simplify the dressing operation and the dressing mechanism by enabling a single dressing tool to effect the dressing of the side and tip surfaces of a grinding wheel in a single continuous operation.

A further object of the invention is to provide a wheel dressing mechanism with which widely varying shapes may be dressed on the side and tip surfaces of a grinding wheel but nevertheless with a single dressing tool in a continuous dressing operation.

A further object of the invention is to provide a dressing mechanism using a single tool, such as a diamond, to dress the sides and tip of the wheel and in which the tool will be maintained at the correct angle to each surface being dressed throughout all of its movements across the sides and tip of the wheel.

A further object of the invention is to provide a dressing mechanism with which a shoulder, even of substantial inclination and even of curved shape, may be dressed on the side of a grinding wheel, so that the Wheel may be used to grind a round or chamfer on the teeth of a clutch member simultaneously with the grinding of the sides of its teeth.

Another object of the invention is to provide an efficient dressing process in which a composite profile, including convex and concave profile portions or including side and tip portions, may be dressed on a grinding wheel while perfect blending is obtained between the various portions of the wheel profile.

A further object of the invention is to provide a dressing mechanism with which each surface of a grinding wheel may be dressed readily in such manner as not to burn the work in the grinding operation. It has been discovered, for instance, that the tip surface of an annular grinding wheel will most likely burn the work unless the spiral path dressed on the tip surface is of substantially the same pitch as the'spiral path dressed on the inside of the wheel. It has been found, too, that ordinarily the outside surface of an annular grinding wheel should be dressed to a coarser pitch than the inside surface of the .wheel to avoid burning. This means that the tip surface of the wheel should bedressed at a substantially constant speed equal to the. speed atjwhich the diamond is moved across. the :inside of the wheel in the dressing ofthe: same, and less than the speed of 'move ment of the. diamond in dressing-the outside of asemm the wheel. The uniformity of dressing of the tip and inside surfaces or the wheel can be obtained to a far greater degree and with much greater ease with the dressing mechanism of the present invention than with dressing mechanisms in which separate dressing tools are employed for dressing the sides and tip or the wheel, yet without interrering with the attainment of the desired coarseneess on the outside of the wheel.

Still another object of the invention is to re duce the length of the path of movementof the dressing tool required to dress the side surface of a grinding wheel and thereby increase the life of the dressing tool employed.

Other objects of the invention will be apparent hereinaiter from the specification and irom the recital of the appended claims.

In the drawings:

Fig. 1 is a fragmentary axial sectional View of an annular grinding wheel ior' grinding one member of a face clutch pair and illustrating somewhat diagrammatically certain principles followed in dressing such a wheel according to th presem invention;

Fig. 2

of an annular wheel such as may be employed in grin the other member of the clutch pair:

Figs. 3 and 4 are fragmentary views illustrating modified forms or face-clutch grinding wheels, and certain principles of dressing such wheels with the method and apparatus or the present invention; 7

Figs. a and 6 are fragmentary sectional views showing two types of gear grinding wheels that may be dressed according to the present'inven- 111011;

Fig. 7 is a sectional view taken in a plane normail to the outside surface of a rotary annular grinding wheel showing the dressing tool in engagement with the outside surface of the Wheel, and illustrating diagrammatically the motions preferably employed with the present invention in dressing this wheel;

Fig. 8 is a corresponding View showing the dressing tool in engagement with the inside surface of a wheel and illustrating diagrammatically the motions that may be employed in dressing this surface Figs. Sand 10 are views similar to Figs. 7 and 8, respectively, illustrating modified methods of dressing the outside and inside surfaces, respectively, of annular grinding wheels;

Fig. 11 is a fragmentary side view of the wheel of Fig. 1, showing the projected path of m'o.ement of its diamond across the outside surface of this wheel; 4

Fig. 12 is a sectional view of a dressing mechanism constructed according to one embodiment of the present invention and adapted particu-' larly for the dressing of grinding wheels of the 1 types shown in Figs. 1 to 4 inclusive;

Fig, 13 is a sectional view taken on the line l3 .l 3 of Fig. 12, looking in the direction of the arrows; y

Fig. 14 is a sectional view taken 'on the line I'd-544 of Fig. 13, looking in the direction of the- BIIOYWS;

Fig. 15 ea fragmentary view showing details of the gearing for operating the-dressingm'echa-- is a fragmentary axial sectional view' Figflfi' is a developed view of the track of the F control cam employed in the mechanism of Fig.

view similar to Fig. 112 but showing- 4 a modified form of control cam such as may be used when dressing a gear grinding wheel of the general type shown in Figs. 5 and 6;

Fig. 18 is an elevational view of a still further form of cam that may be employed in the dressing mechanism when dressing a grinding wheel of either of these types;

Figs. 19, 20 and 21 inclusive are diagrammatic views illustrating successive positions of the dressing tool in dressing a gear grinding wheel according to one embodiment of this invention;

Fig. 22 is a transverse sectional view through the housing showing the rotary piston that actuates the dressing mechanism.

In the embodiments of the invention illustrated, dressing of the desired profile shape on a grinding wheel is efiected during rotation of the wheel by movement of the dressing tool about and along an axis and by swinging the tool about a second axis angularly disposed to the first axis and preferably intersecting the first axis. The

motion in the direction of the first axis is independent'of the motion about that'axis and may take place whileth'e motion about that axis stopped. In dressing a sidesuriace of thewheel, L

the dressing tool is usually swung about the first" axis while being moved in the direction ofthat axis. In dressing the tip'surface of the wheel or a shoulder on the side ofthe wheel; the turn ing motion about the first axis may be stopped and the tip or shoulder may be'dress'ed's'ol'ely by axial motion of the tool inthe direction ofthe' first axis. The swinging m'otion about the second'axis serves to maintain the diamond or other dressing tool at the'correct angle to the surface smooth surfaces may bedressed on the sides and tip of the wheel.

In dressing a grinding wheelthat has a shoul- It operates to maintain the dressing tool der, for instance, the dressing tool may be moved in the direction of the first axis while'the tool is positioned by movement about the second axis so that it makes a constant angle with the surface of the shoulder as it travels across that surface. Then the side of the wheel adjacent the shoulder is dressed by swinging the tool about the second axis to position it' at the correct angle with reference to the side surface, and the tool is swung about the first axis while being moved in the direction of that axis. A round at the juncture of the side'and tip of the wheel may then be dressed by "swinging the tool about the second axis to maintain the tool at the correct angle, while continuing the movements of the tool about and in the direction of the first axis.

The tip of the wheel may be dressed by moving If the position it correctly, and the round at the juncture of the tip and the said opposite side of the wheel is dressedby reversing the direction of taneously feeding the tool further on in the di-,- rection :of. the. first axis. The opposite side of the wheel is then dressed by continuing the swing.

of the tool in the reversed direction about the swin of the tool about the first axis and simul-.

.first axis while feeding the tool further on in the 5. direction of that axis. The swinging movementabout the first axis is, therefore, reversed for dressing opposite sides of the wheel, but in the embodiment illustrated the axial feed movement is continuous in the same direction during dressing of both sides and of the tip of the wheel.

In Fig. 1, 25 denotes a rotary annular grinding wheel such as may be employed in the grinding of one member of a face clutch pair which has longitudinally curved teeth. In the grinding of such clutch members, opposite sides of spaced teeth of each clutch member are ground simultaneously. One member of the clutch pair may have its opposite side tooth surfaces ground with the outside surface of a grinding wheel while 5 the other member of the clutch pair may have its opposite side tooth surfaces ground with the inside surface of a grinding wheel. The wheel 25, shown in Fig. 1, is adapted to grind with its outside surface 26 while the wheel 45 of Fig. 2 is adapted to grindwith its inside surface 45.

The wheel is intended to grind a round alon the tops of the teeth of the clutch member simultaneously with the grinding of the sides of the teeth, the bottoms of the tooth spaces, and the 2 fillet curves which join the sides with the bottoms. For these purposes the wheel is provided with a shoulder 28, an outside surface 25, a tip surface 21, and with rounds 4| and 42, joining the shoulder 23 with the side 26 and the side '26 with the 30 tip surface 21, respectively. The wheel axis is denoted at 40.

For dressing the wheel 25, a diamond 30 may be used. This diamond is swingable about an axis 3| (Figs. 1 and 7), as indicated by arrow 32, and is movable in the direction of the axis 3|, as indicated by arrow 33. It may also betipped about an axis 35, as indicated by arrow 35, which is here shown as passing through the point of the diamond and tangent to the wheel surface.

, The dressing mechanism is preferably so positioned that the axis 3|, about Which the dressing tool rotates and is moved axially, projects into a position parallel to the tip surface 2'! of the wheel and inclined to the normal 38 to the outside surface 25 of the wheel at mean point 39.

The shoulder 28 of the wheel is dressed by first swinging the diamond about axis 35 to incline the dressing tool 30 to the correct angle to surface 28 and by then moving the dressing tool in the direction of the axis.3 I. The round 44 at the juncture of shoulder 28 and side 25 may be formed by swinging the diamond about axis 35 to correctly position the diamond, and then moving the diamond about and in the direction of axis 3|. In the movement about axis 35, axis 3| is returned to the position shown in Figs. 1 and 7. For dressing the side of the wheel, the diamond continues to be swung about axis 3| while being moved in the direction of that axis. The timing of these two movements depends on the shape to bedressed. The path traced by the point of the diamond during dressing of the side surface is shown in projection at 43 in Fig. 11. The round 42 at the juncture of the side surface 26 and 5;, the tip surface 2! is formed by swinging the diamond aboutaxis 35 while continuing to move the diamond about and in the direction of axis 3|. The tip surface 27 may be formed solely by axial motion of the diamond in the direction of the 7G axis 3| after it has been swung around the corner 42. There is no turnin motion required about the axis 3|, the swinging motion about the axis 35 serving to position the diamond at the correct angle to the tipsurface 21.

The various described motions of the diamond take place in a single continuous operation and as the diamond passes over the different surfaces of the wheel, the wheel is, of course, rotated continuously on its axis 40. The diamond is preferably moved at a uniform velocity about and in the direction of axis 3| during the various dressing steps.

The grinding wheel 45 has an inside surface 46, a tip surface 41, an inside shoulder 48, and rounds ,6l and 62, joining the shoulder with the side and the tip surface with the side surface, respectively. For dressing the wheel 45, diamond 50 may be moved about and in the direction of axis 5|, as denoted by the arrows 52 and 53 (Fig. 8), and is tilted about axis 55, as denoted by the arrow 55. The dressing mechanism is preferably positioned as before with axis 5| parallel to the tip surface of the wheel and inclined to a normal at a mean point to the inside surface of the wheel. The shoulder 48 of the wheel may then be dressed by moving the diamond in the direction of axis 5| after it has been positioned at the correct angle to the surface 48 through rotation about axis 55. The round 6| is dressed by swinging the diamond about axis 55 while moving it about and in the direction of axis 5!. The side 48 is dressed by rotatin the diamond about axis 5| while moving it in the direction of that axis. The round 62 is dressed by again swinging the diamond about axis '55 while moving it about and in the direction of axis 5|. Finally the tip surface 41 of the wheel is dressed by moving the diamond in the direction of axis 5|. The wheel 45, of course, rotates on its axis 65, at a uniform velocity throughout the whole of the dressing operation, and, as before, the motions of the dressing tool are preferably all at uniform rates.

Wheels like wheels 25 and 45 are used for grinding face clutch members whose side surfaces are of positive pressure angle. For grinding a face clutch member, whose side surfaces are of zero pressure angle, a wheel such as shown at 65 in Fig. 3 may be employed. This wheel has an outside surface 66 of positive pressure angle and a tip surface 51 which is substantially perpendicular to the outside surface 66. Rounds 12 and i3, respectively, join the side with the tip surface and the side with the shoulder 68, respectively.

For dressing the wheel 65, the dressing mechanism is again preferably positioned so that the axis, about which the diamond rotates and moves axially, is parallel to the tip surface of the wheel. This axis is designated H. In this case, the axis H is normal to the outside surface 65 of the wheel and passes through the mean point 69 of that surface. In the wheel shown, the radii of the convex round 12 and of the concave portion 13 are equal. The various portions of the profile of wheel 55 may be dressed in a manner similar to the methods of dressing wheels 25 and 45, previously described, as will be obvious from the preceding description.

If it is desired to dress a wheel which has a convex round '52 (Fig. 4) at the juncture of side 55' and tip 67 which is of slightly different radius ofcurvature from the concave portion 13' which joins the shoulder 68' and the side 56' of the wheel, this may be accomplished by slightly advancing the diamond from the position which it occupies when dressing the wheel 55 of Fig. 3.

The dotted lines in Fig. 3 show the kind of wheel profile that would be produced if the width of the grinding profile were increased appreciably its-compared with its depth, while still using the samemotions of the dressing tool. The tip surface 61 f the wheel would then become slightly convex, and the shoulder 68 would then be slightly concave.

The axis, about which the diamond is tilted, may be inclined at any suitable angle to the axis about and along which the diamond moves. These two axes need not be at right angles. Thus, as shownin Fig. 9, for dressing a grinding wheel which' is to grind with its outside surface 26, the diamond 30 may again be positioned to move about and along an'axis 3|, as denoted by the arrows 32 and 33, but it may be tipped about an axis 35'-, as'indicated by arrow 36, which passes through the point of the diamond but is disposed at 'an acute angle to the axis 3| and is inclined to the wheel periphery. Likewise, for dressing a grinding wheel '45, which is to grind with its inside surface 46, 'thediamond 59 may be tipped about an axis 55, as indicated by arrow 56', which is inclined at an obtuse angle to axis BI and is inclined to the wheel. surface 39.

The position of the axis, about and along which thedia mon'd moves, may also be varied. Thus, as indicated in Fig. 10, this axis might be at I perpendicular to axis '55 instead of at 5|. In this case, a slightly different profile would be produced on the wheel if the same motions were employed asbefore.

one way in which the'dressing mechanism may be constructed to practice the present invention isillus'trated in'Figs. 12 to 16 inclusive. Here the diamond 'pin or rod 80 is secured, by means of a clamping screw 83, in a split clamp formed at one end of an arm 82. The arm 32 has an elongated shank portion 84, that is secured by a nut 65 in the sleeve portion 86 of a shank-type bevel pinion 87. This bevel pinion is journaled by means of the sleeve portion 86 on anti-friction bearings 88 and 89 in one arm of a generally L- shap'ed holder 90. The other arm SI of this holder iscylind'rical and is mounted to rotate and reciprocate in an elongated sleeve-type anti-friction bearing 92. The balls 93 of this bearing roll on the outside cylindrical surface of arm 9| and on theinside cylindrical surface of the supporting frame or housing 95 of the dresser mechanism.

The arm 91 of the holder 90 has a projection 91 (Fig. 13) at one side which is of general V-shape in cross-section (Fig. 14) and which constitutes a follower thateng ages in the groove or trackway 98 of a cam I00. There is a bar or strap IOI secured in a slot in arm 9! by screws I02. This bar or strap-extends parallel to projection 91 and acts as a follower which engages the periphery of the cam I00 at a point diametrically opposite the point of engagement of the follower 97 with the cam groove 98.

The groove or trackway 98 has a constant depth, that is, its bottom follows the outside contour oi periphery of the cam I99. The groove serves to control the axial motion and axial position of the holder 90. The outside contour 01' trackway of the ca1nI90 controls the rocking 'motion of the holder 90. This rocking motion obviously is controlled only by the shape of the periphery of cam I00 and is independent of the It would be the same shape of the groove 98. if no groove 98 at all were provided in the cam I00. Y r r The cam I00 is keyed or otherwise secured to a shaft I93. This shaft has an armor paddle I04 secured 'to it which constitutes a rotary piston. This piston 'is adapted to operate in a cylinder formed in the frame orhous'i'n'g 95 and between fixed stops (not shown) that are provided lnth'e cylinder. By application of fluid pressure'toone side or the other of the piston I04 through ducts H2 and H2 (Fig. 22), then, the shaft I03 and cam I00 may be oscillated to impart rotary and axial movement to the holder 90, as determined by the shape of cam track 98 and the peripheral surface of the cam.

Connected to the shaft I03, as by means of a conventional face clutch I05, is a spur gear I06. This spur gear, which is shown in dotted lines in Fig. 15, 'meshes'with another spur gear I0! that is mounted on a countershaft (not shown) which is journaled in the frame or housing 95 parallel to the shaft I 03. The axisof this countershaft is I denoted at I I2; 7 U

Secured tothe shaft I03 to rotate with the gear I06 is a segmental gear I08, and secured to the countershaft to rotate with the gear I01 is another segmental gear I09. The two segmental gears are adapted to engage with and drive intermittently-a gear'l I0 which is keyed to a sleeve I I I (Fig. 12).

This sleeve III is journaled on anti-friction bearings I I3 in the housing 95 and it is keyed to one 'end of a shaft 'I I4. The shaft I I4 is jou'rnalled at its opposite 'end on an anti-friction bearing H5 which is secured in the arm 9| of the holder 90. The shaft I I4 is coaxial with the arm SI of holder 99 and its 'axisII'I corresponds to the axis SI of Figs. '7 and 9. V

Integral with the shaft H4 is a bevel gear H6 which meshes with the'bevel pinion 81. The segmental gears I08 and I09 serve to drive the shaft II 4 intermittently, first 'inone direction and then in the other, thereby swinging the arm 82 and the diamond 80, first in one direction and then in the other about the axis I23 of rotation of said arm 82, which axis corresponds to the axis 35 of Fig. 9. The spur gear I I0 'is held in its end positions by means of a ball II 8. This ball is pressed by a coil spring II9 into one or the other of two suitably shaped recesses I20 which are provided on the hub of gear 0. The coil spring H9 is housed in an opening in a partof frame or housing '95. The recesses I20 are so shaped that each provides a positive stop in one direction while permitting the gear to be moved in the opposite direction toward the other stop if suificient'force is'applie'd.

From the preceding description, it will be seen that as the paddle or piston I04 is rotated in one direction or the other through fluid pres-'- sure, the cam shaft I03 will be swung corr'espondingly and the cam I00 will be swung cor respondingly. The swinging cam will oscillate tool holder about axis II'I through operation of flat follower I0'I, and it will move tool holder 90 in the direction of axis II'I through operation of cam track 98 and follower 91. The swingingshaft I03 will also swing tool arm 82 intermittently first in one direction and then in the other through operation of gears I09, I01, I08, I09,. H0, H6 and 31. The times, duration, and di- 1 rection of swinging movement about axis I I! will depend upon the shape of the periphery of;- ca'm I00 and the direction of swing of the cam. The times, duration, and direction of movement along axis III will depend upon the contour of trackway 98 and the direction of swing of the. cam. The times, direction and duration of swing of the tool about axis I23 will depend upon the angular positions of the segmental gears I08 5 and I09 about their respective axes "I2! Send, :I like.

the length of the toothed portions of the gears,

and the direction of swing of shaft I03.

Thus, it will be seen that by providing a suitable control cam and suitable gearing, differing shapes of profile can be dressed on a grinding wheel. Moreover, the housing 95 may be mounted adjustably on the grinding machine with the same adjustments as disclosed in the patent of myself and Leonard O. Carlsen No. 2,311,302, issued February 16, 1943, thereby permitting further variation in the shapes that may be dressed on the side surfaces of the wheel, both convex and concave.

In Fig. 16 the cam I is shown as provided with a groove or trackway 98, such as would be required for dressing a grinding wheel of the type shown in Figs. 3 and 4. This groove or trackway has a portion 98' which extends in the peripheral direction, and'portions 981 and 982 which are inclined to the peripheral direction. The portions 081 and 982 produce motion of the diamond holder 90 along the axis III, while the portion 98' is a dwell portion and serves to hold the diamond in fixed axial position. As the cam I00 is turned through its angle of swing from one end to the other, the groove 98 through its engagement with the arm 91 moves the holder 90 axially, then gradually stops said axial motion, and then later causes resumption of the axial motion in the same direction as originally. This axial motion combines with the turning motion produced by the cam contour through the flat follower IOI to give the desired shape to the grinding wheel. For profiles, such as shown in Figs. 1 and 2, the central portion 98 of the groove 98 would be inclined to the periphery of the cam in the same direction but less than the end portion 981 and 982.

The cam I00 may have any desired peripheral contour. Ordinarily, a circular shape is satisfactory and is preferred because of its simplicity. Thecam contour or trackway may be, for instance, a' circle centered at I20 (Fig. 13), that is, at a point offset from the axis I2I of rotation of the cam shaft I03. In the turning motion of the cam I00, then, the center I20 of the peripheral contour of the cam describes a circular arc I22 about the axis I2I. The end positions of movement of the center I20 in the swing of the cam are denoted at I20 and I20", respectively. The center I20 moves between the positions I201 and I202 while the diamond is dressing theside surface 66 (Fig. 3) of the grinding wheel 65. The center moves between the positions I20" and I203 while the diamond is dressing the tip portion 61 of the wheel. The

center moves between positions I203 and I201 while the diamond is dressing the rounded portion I2 of the wheel profile. While the center moves between positions I202 and I20 adjacent point I202, the diamond dresses the concave chamfer surface I3 of the wheel, and while the center is moving adjacent position I20, the diamond dresses the straight shoulder portion 68 of the wheel. The diamond holder 90 has then ceased to move appreciably about its axis I I1 and moves only along said axis. The same is true while the center of the wheel contour is moving between positions I20" and I203. As the point of the dressing tool moves over the grinding wheel profile, the diamond point is continuously maintained at the desired constant inclination to the grinding surface by being turned intermittently about axis I23. Thus, a smooth surface is dressed on the wheel.

In the'grinding wheels shown in Figs. 1 and 2, the radii of the convex and concave portions of the wheel profiles are equal. For instance, the radius of concave portion II of wheel 25 is the same as the radius of convex round 42. If desired, these radii can be made unequal by simply adjusting diamond pin 30 (Fig. 7 along its axis 3i Without changing control cam I05. In this case, the axis 35 or 35 no longer passes through the point of the diamond. The diamond then traces a profile, such as shown in dotted lines in Fig. 1, which is equidistant from the profile shown in full lines. Similarly, the dotted line profile might be produced on the wheel 45 (Fig. 2) simply by adjustment of diamond pin 50 along axis 5I without change of the control cam.

For grinding gears or threads, wheels of contours, such as shown in Figs. 5 and 43, are used. The grinding wheel I25, shown in Fig. 5 has straight profiled sides 52B and I21 that converge to its tip I28. The tip may be fiat, as shown, with rounds I29 and I30 joining it to the sides I 26 and I2'I, respectively, or it may be fully rounded, as shown in dotted lines at I28. Such a wheel might be of the disc, cupped, or annular type. The wheel I35, shown in Fig. 6, has a convex outer side surface I35 and a concave inner side surface I31 and is of either annular or cupped type. Its tip I38 may be fiat or fully rounded.

For dressing wheels of the types shown in Figs. 5 and 6, a somewhat different form of control cam may be employed. This cam I40 (Fig. 17) may have a circular periphery, but will be swung through a greater are I42 for dressing the two sides of a wheel than the arc I22 of swing of cam I00 in the dressing of a wheel which is to grind with one side only. The center of cam I40 is at MI in the mean position of dressing the outside surface of the wheel. The different positions of the center of the cam contour as the cam oscillates on axis I2I are denoted at I4I1, I4Iz, MI, and MI" respectively.

As the cam I40 is swung by swing of shaft I03 to move the center of the cam periphery from position I4I1 to position I IIz, one side of the wheel is dressed. As the cam center moves from I4Iz to I4I the tip of the wheel is dressed as a complete round like the round I28 of Fig. 5. The opposite side of the wheel is dressed as the cam center moves from position I4I' to position MI".

The cam permits of dressing the outside surface of an annular grinding wheel at greater speed than the inside surface of the wheel while still dressing both sides with uniformmotion of the diamond. With faster dressing, the outside surface of the wheel will be of coarser pitch than the inside surface and will be less likely to burn the work. The pressure exerted on the rotating wheel by centrifugal force tends to press the outside of the wheel against the work, and, if the outside of the wheel is dressed too fine, the outside of the wheel will burn the work. Slow uniform rotation of the diamond holder about axis III i effected while the center of the cam is moving between positions I4I and MI while faster uniform rotation of the holder 90 about axis II! is achieved during the time the center of the cam is moving between positions I4I1 and I4I2.

Instead of the cam I40, which has a circular periphery and is mounted eccentrically of the shaft I03, a cam, such as shown at I50 in Fig. 18, mayalso be used. The cam I50 has two cy- '19. to 21. inclusive.

ing between the points I532and I54 of the. cam periphery and the portion I52. lying between the points. I51.v and 158. The. two portions I5I. and

I52 are generated. conjugate to the plane contacting surface of the follower IBI andlike cam "I40 they. effect slowiuniform rotationof; thediamondhold-er 96 about axis II1 when the cam is moving in one partof its swing and. faster uniform. rotation of the holder 96 about. axis II! when the cam is moving in another part of its swing. The. cam periphery also containstwo directly opposite circular arcuate portions SI and I62 which are centered at I63, oifset from the axis I.2I of the cam shaft. The cam I50 has two other diametrically opposite circular arcuate portion I 65. and I66, which are centered at I61 also offsetfrom the. aXisIZI "of the cam shaft. Circular arcuate portion I6I lies between the pointsIiLand I55. of. the cam. periphery. Circu- -.lararcuate.portion: I55 lies between the points I56- and I51 of. the camperiphery, Circular ar- --cuate.portion I 62 liesbetween the points 158 and .I;59.of;the. cam periphery. Circular arcuafeportion I66. liesbetweenlthe points. IGIland I53 of the cam periphery.

lar arcuate portions I62 and I66 are engaging follower 91; Partial reversal is made before the tip. surface of .the wheel isdressed and the re- .mainder afterzthe tip surface is dressed. The circular arcuate portions I10. and HI are dwell .portions which are .in. operative position. during dressing of: the tip. surface. They permit obtaining. flat tip .surfaces, such as shown in full .linesat. I28 and I38 in Figs. 5 and 6. The diamond; holder swings about its axis I51 in the opposite direction during the dressing of the inside surface of the grinding wheel .from .that in which. it. swings. during dressing of the outside surface of the wheel.

The Way in which the dressing mechanism operates when a .camof the type shown in Fig. 18

is used is illustrated diagrammatically in Figs. Here I denotes the wheel to be. dressed and HI is the wheel axis, the wheel shownbeing of the annular type. In dressing the. outsidesurface I26 of the wheel, the diamond .is, swung. about axis H1 in. the direction of the 1 I26 and the tip I28 of the wheel is dressed. Then the swinging movement about axis II'I ceases, but the diamond continues to move in the direction of axis II1, as denoted by arrow I16 in Fig.

20. This causes the diamond to move from position 801 to position 862 to dress the tip surface .I28 of'the wheel. Then, asdenoted in'-.Fig. 21,

the diamondholder is swung about. thegaxis: I23 in the same direction as before,v ascindicatedby arrow I13,.(Fig. 21). and throughmovementabout and in. the direction; of axis: [I], the diamond dresses the round. I36 on: thewheel. During .the dressing of the tworounds, the direction of. swing of. thediamond about axis II.1: may. be reversed. Thenv the diamond dresses the insidesurface I21 of. the wheel by beingswung about axis I I1.in.the 19 directioniof the arrow H9. while still moving in the direction of. the arrow; I15. along the axis III. Both motions are atuniform. velocity but at a relatively slow rate ascomparedwith-the, dressing of. outsidev surface :26. In these movements, 1 the diamond passes. from position 80ato80b, and

One dressing pass over, the wheel is completed. The two. sides andthe. end of the wheel may, therefore, be,v dressed in. a singlev swing of: the control cainaboutv axis i2I. lfdesiredlhowever, 2 another dressing pass. may be....had during-the return swing-of the cam to starting-position.

- While the: shiesare being dressedthe pointof the diamond is maintained at 1a .co'nstant or subfstahtiallv constant position with referencetto axis; I23 .but. itis turned about. axis; I.2.3 .while. the roundsat the corners of the sides and tipof. the wheel; are. dressed. If the. wheel has-a. fiat tip and roundsare being dressed on they corners formed at. the junctures at. the opposite sidesof 39 the, wheel and the tip, theturning motion about axis I23 may bemarle in two steps .if desired. If the, wheel is, to have. a. fully rounded tip, .as shown in dotted lines at I28, in Fig. 5, then the swing about axis I23. is madein one step. In any event, where dressing. of. bothinside and out side surfaces. of the wheel is to beeffected, one of the; segments I08 or H13 (Fig. 15) isomitted.

The othersegment is made. longer than shown. in

that figure and, if the turningcmotion about. axis 40 5.23. is to be. effectedintwosteps, .its teethare arranged in two groups.. around its periphery with a gap betweenthe-two. groupsof teeth.

To dress. a. convex or a. concave side surface on awheel, such; as:.is.re'quiredinthe. case of the wheel I35.of;Fig. 6, obviously all thatis necessary is; to properly. time the motion of the tool holder 90 along. axis.v I.I1.:.with its motion aboutthat axis. If the, curvature of. the sides. is: considerable. it maybe desirable, also, to tiltthe diamond about axis I23. duringthe. dressing ofxthesides. so. as to maintain: the diamond at.a desirable dressing angle .to..the.wheel surface during dressing. The motions-about and in thedirection of. axis II'i andrabQutaXis IZB are all independent. of one another;amhanycdesired shape can be dressed on; a grinding; wheel simply.. .by-selection of the proper'control cam and of. the-.propersegmental ears. While; the invention hasbeendescribed particularly with reference to the dressing of'annular type-grinding wheels, it will be understood :thati it. is applicable to the dressing-0f any grind- -ing wheel. of varying; proflleshape, whether that wheel be' a cuppedadisc; or anyother type-of grinding wheel-z 'It will be understood, further, that Awhile the-invention has. been described in connection with certain embodiments. thereof it is capable of various further modifications and thepresent application is intended to cover any variationsnses, or adaptations of the invention following, in general, the-principlesof the invention andincl-uding such departures from'the'pres- Y ent' disclosure as comewithin-known orcustomary practice inthe art to which the invention per- 7 tains and as may be appliedto the essential features here'inbefore set forth and as fall within the scope of the invention or the limits of the appended claims.

Having thus described my invention, what I claim is:

1. The method of dressing side and tip surfaces of a grinding wheel which comprises swinging a dressing tool across a side surface of the wheel while moving it in the direction of its axis of swing to dress the side surface of the wheel, then swinging the tool about an axis inclined to the first axis to position the tool at substantially the same angle to the tip surface as to the side surface, and then moving the tool in the direction of the first axis to cause it to dress the tip surface of the wheel.

2. The method of dressing side and tip surfaces of a. grinding wheel which comprises engaging a dressing tool with a side surface of -a grinding wheel, moving the dressing tool in two directions.

at right angles to one another to dress the said side surface of the wheel, and then swinging the tool around the corner at the juncture at the side and tip surfaces of the wheel so that it will have substantially the same angle to the tip surface as to the side surface, and then moving the tool in one of the first named directions to dress the tip of the wheel.

3. The method of dressing side and tip surfaces of a grinding Wheel, which comprises swinging a dressing tool across a side surface of the wheel while moving it in the direction of its axis of swing to dress the side surface of the wheel, then swinging the tool about an axis inclined to the first axis to position the tool at substantially the same angle to the tip surface as to the side surface, and then moving the tool in the direction of the first axis to cause it to dress the tip surface of the wheel, the first axis extending in the direction of the tip surface of the wheel.

4. The method of dressing side and tip surfaces of a grinding wheel, which comprises imparting movement to a single dressing tool in two directions at right angles to one another to dress one side surface of the wheel, then swinging the tool around the corner at the juncture of said side surface and the tip surface while continuing to impart movements in the first two directions to the tool, then moving the tool in one of the first named directions to dress the tip of the wheel, then swinging the tool in the same direction as before to turn it around the corner at the juncture of the tip surface and the opposite side surface of the wheel while moving the tool in;

the same direction as for tip dressing and in a direction at right angles thereto but opposite to the direction of the first named movement, and then dressing the opposite side of the wheel by continuing the last two namedrnovements.

5. The method of dressing one side, the tip, and the opposite side surface successively of a grinding wheel which comprises engaging a dressing tool with a side of the grinding wheel, swinging the dressing tool about one axis while moving the tool in the direction of said axis to dress said side of the wheel, then swinging the tool about an axis inclined to the first named axis, then moving the tool in the direction of the first named axis further in .the same direction as before to ,dress the tip of the wheel, then swinging the tool again about the second axis, then swinging the tool about the first axis but in a direction opposite to the direction of previous swing about that axis while continuing to move the tool,

14 axially of said axis and in the same direction as previously to dress the opposite side of the wheel.

6. The method of dressing one side, the tip, and the opposite side surface successively of a grinding wheel, which comprises engaging a dressing tool with a side of the grinding wheel, swinging the dressing tool about one axis while moving the tool in the direction of said axis to dress said side of the Wheel, then swinging the tool about an axis inclined to the first named axis, then moving the tool on further in the direc tion of the first named axis to dress the tip of the wheel, then swinging the tool again about the second axis, and then dressing the opposite side of the wheel by swinging the tool about the first axis but in a direction opposite to the direction of previous swing about that axis while continuing to move the tool axially of that axis and in the same axial direction as previously, the first axis being parallel to the tip surface of the wheel.

7. The method of dressing side and tip surfaces of a grinding wheel which comprises moving a dressing tool about and along an axis, and moving the tool about a second axis inclined to the first axis, the tool being moved axially of the first axis in the same direction during dressing of the side and tip surfaces, and being swung about said axis during dressing of the side surface, at least, and being swung about the second axis to maintain the tool at substantially a constant angle to the different surfaces being dressed during dressing of the same.

8. The method of dressing opposite side and tip surfaces of a grinding wheel which comprises moving a dressing tool about and along an axis, and moving the tool about a second axis inclined to the first axis, the tool being moved axially of the first axis in the same direction during dressing of the tip and both side surfaces, and being swung about said axis during dressing of the side surfaces, at least, the swingingmovement being in one direction during dressing of one side of the wheel and in the opposite direction during dressing of the opposite side of the wheel, and the tool being swung about the second axis to maintain the tool at a substantially constant angle to the surfaces being dressed during dressing of the same. 7

9. The method of dressing surfaces on a grinding wheel which are of different inclination to the Wheel axis, which comprises moving a dressing tool about and along an axis, and moving the tool about an axis inclined to the first axis, the tool being moved axially of the first axis during dressing of the different' surfaces, and being moved about the first axis during dressing of one surface, at least, and being swung about the second axis to maintain the tool at a substantially constant angle to the surfaces being dressed during the dressing of the same.

10. The method of dressing the tip and opposite side surfaces ofa grinding wheel with a single dressing tool which comprises moving the tool about and along an axis to dress one side of the wheel, then swinging the tool about a second axis angularly inclined to the first axis while continuing to move the tool about the first axis to dress the tip of the wheel, and

:then moving the tool about and along the first axis to dress the opposite side of the wheel, the

tool being swung about the first axis in oppo- :site directions during the dressing of the opposite sides of the wheel but being moved axially of that axis in the same direction during the dressing of the two sides of the wheel.

11. The method of dressing opposite sides surfaces of a grinding wheel which comprises dressing one side surface of the wheel by swing- .ing a dressing tool across this surface while moving the tool in one direction along its axis of swing, and dressing the opposite side surface of the wheel by swinging the tool in the opposite direction while continuing to move the tool along itsaxis of swing in the same direction as. during the dressing of the first side of the wheel.

12. The method of dressing opposite side sur-- faces of a grinding wheel which comprises dressing one side surface of the wheel by swinging the dressing tool across said surface about an axis which lies in a plane perpendicular to the axis of the wheel while moving the tool along said first-named axis, and dressing the opposite side surface of the wheel by swinging the tool in the opposite direction about said first-named axis while continuing to move it along said first-named axis in the same direction as during dressing of the first side of the Wheel.

13. The method of dressing opposite side surfaces of a grinding wheel which comprises dressing one side of the wheel by swinging a dressing tool in one direction about an axis which lies in a plane perpendicular to the axis of the wheel while moving the tool along the first-named axis, and dressing the opposite side surface of the wheel by swinging the tool in the opposite direction about said first-named axis while continuing to move the tool along said first-named axis in the same direction as during dressing of the first side of the wheel, the tool being swung about said first-named axis at different rates of speed during dressing of the opposite sides, respectively, of the wheel. 14. In apparatus for dressing grinding wheels,

" in combination, a frame, a tool holder mounted holder for movement about an axis inclined to the axis of the tool holder, a dressing tool secured in said tool support, a rotary cam having a double trackway formed thereon, means operatively connecting the tool holder to one of the two trackways to impart rotary movement to the tool holder on rotation of the cam; means operatively connecting the tool holder to the other trackway to impart axial movement to the tool holder as the cam rotates on its axis, means operatively connected to the cam for rotating the cam, and means driven in time with the last-named means and operatively connected to the tool support for intermittently rotating the tool support on its axis.

15. In apparatus for dressing the sides and tip of a grinding wheel, in combination, a pointed rod-type dressing tool, an arm for supporting the same, means operatively connected to said arm' for swinging said arm about one axis. means operatively connected to said arm" 'for moving said arm in the direction of said arm is moved continuously in one direction axially of the first axis during said movement of the dressing tool successively across said one side, the tip, and said other side of the wheel, said first-named means being constructed to swing the arm in one direction about the firstnamed axis during dressing of said one side of the wheel and to swing the arm in the opposite direction about the first-named axis during dressing of said other side of the wheel, and the third-named means being constructed to swing the arm about the second axis during operation of either of the first two means to maintain the dressing tool at the correct angle to all of the wheel surfaces duringv dressing of said surfaces.

16. In apparatus for dressing grinding wheels, in combination,. a housing, a tool holder mounted in the housing for rotary movement about an axis and for bodilytranslatory movement along that axis, a tool support mounted in said holder for, rotary movement independently of the holder about an axis inclined to the axis of rotation of the holder, a pointed, rod-like dressing tool mounted on the tool support, means operatively connected to the tool holder for swinging the tool holder on its axis, separate means operatively connected to the tool holder for moving the tool holder in the direction of its axis, and means operatively connected to the tool support for swinging the tool support on its axis during movement of the tool holder to maintain the dressing tool at the correct angle to the surface, which is being dressed, during movement of the tool holder.

17. In apparatus for dressing grinding wheels, in combination, a housing, a tool holder mounted in the housing for rotary movement about an axis and for bodily translatory movement along that axis, a tool support mounted in said holder for rotary movement independently of the holder about an axis inclined to and intersecting the axis of rotation of the holder, a pointed, rod-like dressing tool mounted on the tool support, means operatively connected to the tool holder for swinging the tool holder on its axis, separate means operatively connected to the tool holder for moving the tool holder in the direction of its axis, and means operatively connected to the tool support for swinging the tool support on its axis during movement of the tool holder to maintain the dressing tool at the correct angle to the surface, which is being dressed, during movement of the tool holder.

18. In apparatus for dressing grinding wheels, in combination, a housing, a tool, holder mounted in the housing for rotary movement about an axis and for bodily translatory movement along that axis, a tool support mounted in said holder for rotary movement independently of the holder about an axis inclined to the axis of rotation of the holder, a pointed, rod-like dressing tool mounted on the tool support, means operatively connected to the tool holder for swinging the tool holder intermittently about its axis, separate means operatively connected to the tool holder for moving the tool holder in the direction of its axis, and means operatively connected to the tool support for swinging the tool support on its axis during movement of the tool holder to maintain the dressing tool at the correct angle to the surface being dressed.

19. In apparatus for dressing grinding wheels, a housing, a tool holder mounted in said housing for movement therein in two directions at right angles to one another, one of said movements, at least, being rectilinear, a rotary tool arm mounted on said tool holder for movement about an axis inclined to one of the two di rections of movement of the tool holder, a pointed, rod-like dressing tool secured in said arm to project radially beyond the arm, separate means operatively connected to the tool holder to move the tool holder in each of its two directions of movement, and means operatively connected to said am to move the arm about its axis during movement of the tool holder.

ERNEST WILDHABER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES F'ATENTS Number Name Date 314,469 Perkins Mar. 24, 1885 1,187,459 Lumsden June 20, 1916 1,323,486 Olson Dec. 2, 1919 1,698,909 Currier Jan. 15, 1929 1,759,196 Jackson May 20, 1930 1,985,409 Hill Dec. 25, 1934 2,144,459 Lively Jan. 1'7, 1939 2,304,970 Turner Dec. 15, 1942 2,311,262 Stewart Feb. 16, 1943 2,313,055 De Vlieg Mar. 9, 1943 2,317,411 Seyferth Apr. 27, 1943 FOREIGN PATENTS Number Country Date 416,336 Great Britain Sept. 11, 1934 

